Allegro MicroSystems Inc.'s complete three phase brushless DC
motor pre-driver has outputs for direct high current gate drive of an all
N-channel power MOSFET. The three phase bridge has a maximum supply voltage of
38 V. The A4938 includes Hall element inputs, a sequencer
for commutation control, fixed off time pulse width modulation (PWM) current
control and locked rotor protection. Output current is scalable with the choice
of external MOSFETS. ENABLE, DIRECTION and BRAKE inputs can be used to control
the motor, speed, position and torque. Output speed can be regulated using open
drain FG1 output that changes state at each Hall transition.
external MOSFETS can be PWM'd with the ENABLE input or with the internal PWM
current regulator. In both cases the A4938 synchronous rectification feature
will turn on the appropriate MOSFET(s) during current decay to reduce power
dissipation. The A4938 uses low cost Hall elements with noise filtering to
prevent false commutation signals. A 5V regulated supply output is provided to
power the three HALL elements. Internal circuit protection includes thermal
shutdown with hysteresis, under voltage lockout, over voltage protection with
two voltage settings, locked rotor and dead time protection. Special power up
sequencing is not required. Operating temperature range is -40 to 85C. The A4938EETTR-T is supplied in a 5 ×
5 mm 28-lead QFN package with exposed thermal pad.
A flyer or flier, also called a circular, handbill or leaflet, is a form of paper advertisement intended for wide distribution and typically posted or distributed in a public place or through the mail.
Halloween isn’t just a time for creative costumes. Thanks to the element14 online design community, the holiday this year also brings us a number of creative electronic device design ideas aimed at making your Halloween party a unique experience.
On April 15, 2010, President Barack Obama gave a major speech at the Kennedy Space Center in Florida, announcing that the US would send astronauts to Mars by the mid-2030s. But in order to do so, NASA would first need to ramp up its capabilities through missions directed toward "a series of increasingly demanding targets," i.e. asteroids.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.